Vascular/venous access devices for introducing catheters into a patient's vascular system are well known. The simplest of such devices comprises a through-the-needle catheter which is inserted via a cannula. The cannula generally comprises a metal needle inserted into the patient's vein through which the catheter is subsequently introduced.
A common problem associated with the use of such prior art through-the-needle catheter systems arises in removing the cannula after the catheter has been introduced into the vein. Since the cannula is typically comprised of a rigid metal needle, it is desirable to remove the cannula from the patient's vein after insertion of the catheter to prevent trauma to the vein caused by the cannula's rigid structure and/or sharp tip. However, once the catheter has been inserted into the vein, the cannula can typically only be removed by retracting the same upwardly along the catheter, thereby undesirably exposing the patient as well as administering personnel to accidental contact with the cannula.
In recognizing the problems associated with through-the-needle catheter systems, over-the-needle catheter systems have become widely utilized for venous/vascular access applications. In such over-the-needle catheter systems, a thin catheter having a hub at its proximal end is placed over a rigid cannula, such as a needle, whereby the cannula as well as the catheter are simultaneously inserted into the vein of a patient. Once the cannula and catheter have been introduced into the vein, the cannula may be withdrawn from the interior of the catheter, leaving the catheter disposed within the patient's vein. Subsequently, required administration line communication can be effectuated with the catheter by interconnection with its hub mounted to the proximal end of the catheter.
One problem commonly associated with such contemporary over-the-needle catheters is that they tend to travel axially away from the tip of the needle and thus collapse during the insertion process. The skin and tissue tend to push the distal tip of the catheter body backward, or proximally resisting the introduction of the distal end of the catheter therethrough. The catheter body thus wrinkles in an accordion or bellows-like manner over the needle as the distal end of the catheter travels backward toward the proximal end thereof while the needle of the introducer is urged through the skin and tissue.
Thus, such contemporary over-the-needle catheters must possess sufficient rigidity to prevent the same from traveling axially backward relative to the cannula upon which they are disposed during the insertion process. Because of the need for such rigidity, contemporary over-the-needle catheters are incapable of being inserted through the length of a vein or artery without causing substantial trauma and/or puncture thereto.
Another problem associated with such over-the-needle catheters is that the opening in the distal tip thereof occasionally becomes either completely or partially obstructed, thus mitigating fluid flow through the catheter. Various types of particulate matter may facilitate such plugging of the opening in the distal tip of the catheter. For example, small pieces of tissue, i.e., skin, fatty tissue, vascular tissue, etc., may plug the tip of the catheter.
As such, although contemporary over-the-needle catheters have proven generally suitable for their intended purposes, they possess inherent deficiencies which detract from their overall effectiveness and reliability. Moreover, it is desirable to provide an improved over-the-needle catheter which is not subject to becoming compressed during the insertion process and yet which is not so rigid as to cause trauma to blood vessels and the like. It is also desirable to provide an improved over-the-needle catheter which will continue to allow fluid flow therethrough in the event that the opening in the distal end thereof becomes plugged.